1. Field of the Invention
The present invention relates generally to an illuminating device used for a display unit, and more particularly to a light reflector used with a light-transmission type display unit, for instance, such as a liquid crystal display unit in which a plurality of light sources are arranged between the display panel and the light reflector at regular intervals.
2. Description of the Prior Art
Recently, various light-transmission type display units such as liquid crystal display or electrochromic display have been utilized for displaying various indications outputted from a device or apparatus or instruments arranged in a dashboard of, for instance, an automotive vehicle.
The liquid crystal display unit can be classified into roughly three types from the standpoint of light-transmitting method, that is, full transmission type, half transmission type, and reflection type. In the full transmission type, the light source is usually disposed at the back of a liquid crystal display panel in order to display some letters or figures in dependence upon the light emitted from the light source. In the half transmission type, the light source is usually disposed at the back of a liquid crystal display panel and a half mirror is additionally provided between the display panel and the light source in order to display some letters or figures in dependence upon the light received from the outside in the daytime and the light emitted from the light source in the nighttime. In the reflection type, a reflector plate is usually disposed at the back of a display panel in order to display some letters or figures in dependence upon the light received only from the outside.
In the transmission type display unit, since a point source such as bulb lamp or a line light source such as fluorescent lamp is used, it is not easy to display the figures on the liquid crystal display panel under a uniform brightness. To overcome this non-uniformity in brightness on the display panel, a parabolic reflector or a diffusion plate (diffuse reflector) is used, being disposed at the back of the liquid crystal display panel. In the case of the parabolic reflector, there exists a problem in that the brightness on the display panel is not satisfactorily uniform; in the case of the diffusion plate, there exists a problem in that an additional element is required and further the brightness is reduced markedly throughout the display panel.
A more detailed description of the prior-art parabolic reflector used with a display unit will be made with reference to the attached drawing under Detailed Description of the Preferred Embodiment.